/*
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.
*/
// Copyright 2010
// Author: Zihan Liu (updogliu@tencent.com)
//
// This file comes from http://sourceforge.net/projects/libmd5-rfc/files/

#include <string.h>
#include <string>

#include "src/base/common.h"

typedef unsigned char md5_byte_t;  /* 8-bit byte */
typedef unsigned int md5_word_t;   /* 32-bit word */

/* Define the state of the MD5 Algorithm. */
typedef struct md5_state_s {
  md5_word_t count[2];         /* message length in bits, lsw first */
  md5_word_t abcd[4];          /* digest buffer */
  md5_byte_t buf[64];          /* accumulate block */
} md5_state_t;

inline void md5_init(md5_state_t *pms);
void md5_append(md5_state_t *pms, const md5_byte_t *data, int nbytes);
void md5_finish(md5_state_t *pms, md5_byte_t digest[16]);


#undef BYTE_ORDER /* 1 = big-endian, -1 = little-endian, 0 = unknown */
#ifdef ARCH_IS_BIG_ENDIAN
#  define BYTE_ORDER (ARCH_IS_BIG_ENDIAN ? 1 : -1)
#else
#  define BYTE_ORDER 0
#endif

#define T_MASK ((md5_word_t)~0)
#define T1 /* 0xd76aa478 */ (T_MASK ^ 0x28955b87)
#define T2 /* 0xe8c7b756 */ (T_MASK ^ 0x173848a9)
#define T3    0x242070db
#define T4 /* 0xc1bdceee */ (T_MASK ^ 0x3e423111)
#define T5 /* 0xf57c0faf */ (T_MASK ^ 0x0a83f050)
#define T6    0x4787c62a
#define T7 /* 0xa8304613 */ (T_MASK ^ 0x57cfb9ec)
#define T8 /* 0xfd469501 */ (T_MASK ^ 0x02b96afe)
#define T9    0x698098d8
#define T10 /* 0x8b44f7af */ (T_MASK ^ 0x74bb0850)
#define T11 /* 0xffff5bb1 */ (T_MASK ^ 0x0000a44e)
#define T12 /* 0x895cd7be */ (T_MASK ^ 0x76a32841)
#define T13    0x6b901122
#define T14 /* 0xfd987193 */ (T_MASK ^ 0x02678e6c)
#define T15 /* 0xa679438e */ (T_MASK ^ 0x5986bc71)
#define T16    0x49b40821
#define T17 /* 0xf61e2562 */ (T_MASK ^ 0x09e1da9d)
#define T18 /* 0xc040b340 */ (T_MASK ^ 0x3fbf4cbf)
#define T19    0x265e5a51
#define T20 /* 0xe9b6c7aa */ (T_MASK ^ 0x16493855)
#define T21 /* 0xd62f105d */ (T_MASK ^ 0x29d0efa2)
#define T22    0x02441453
#define T23 /* 0xd8a1e681 */ (T_MASK ^ 0x275e197e)
#define T24 /* 0xe7d3fbc8 */ (T_MASK ^ 0x182c0437)
#define T25    0x21e1cde6
#define T26 /* 0xc33707d6 */ (T_MASK ^ 0x3cc8f829)
#define T27 /* 0xf4d50d87 */ (T_MASK ^ 0x0b2af278)
#define T28    0x455a14ed
#define T29 /* 0xa9e3e905 */ (T_MASK ^ 0x561c16fa)
#define T30 /* 0xfcefa3f8 */ (T_MASK ^ 0x03105c07)
#define T31    0x676f02d9
#define T32 /* 0x8d2a4c8a */ (T_MASK ^ 0x72d5b375)
#define T33 /* 0xfffa3942 */ (T_MASK ^ 0x0005c6bd)
#define T34 /* 0x8771f681 */ (T_MASK ^ 0x788e097e)
#define T35    0x6d9d6122
#define T36 /* 0xfde5380c */ (T_MASK ^ 0x021ac7f3)
#define T37 /* 0xa4beea44 */ (T_MASK ^ 0x5b4115bb)
#define T38    0x4bdecfa9
#define T39 /* 0xf6bb4b60 */ (T_MASK ^ 0x0944b49f)
#define T40 /* 0xbebfbc70 */ (T_MASK ^ 0x4140438f)
#define T41    0x289b7ec6
#define T42 /* 0xeaa127fa */ (T_MASK ^ 0x155ed805)
#define T43 /* 0xd4ef3085 */ (T_MASK ^ 0x2b10cf7a)
#define T44    0x04881d05
#define T45 /* 0xd9d4d039 */ (T_MASK ^ 0x262b2fc6)
#define T46 /* 0xe6db99e5 */ (T_MASK ^ 0x1924661a)
#define T47    0x1fa27cf8
#define T48 /* 0xc4ac5665 */ (T_MASK ^ 0x3b53a99a)
#define T49 /* 0xf4292244 */ (T_MASK ^ 0x0bd6ddbb)
#define T50    0x432aff97
#define T51 /* 0xab9423a7 */ (T_MASK ^ 0x546bdc58)
#define T52 /* 0xfc93a039 */ (T_MASK ^ 0x036c5fc6)
#define T53    0x655b59c3
#define T54 /* 0x8f0ccc92 */ (T_MASK ^ 0x70f3336d)
#define T55 /* 0xffeff47d */ (T_MASK ^ 0x00100b82)
#define T56 /* 0x85845dd1 */ (T_MASK ^ 0x7a7ba22e)
#define T57    0x6fa87e4f
#define T58 /* 0xfe2ce6e0 */ (T_MASK ^ 0x01d3191f)
#define T59 /* 0xa3014314 */ (T_MASK ^ 0x5cfebceb)
#define T60    0x4e0811a1
#define T61 /* 0xf7537e82 */ (T_MASK ^ 0x08ac817d)
#define T62 /* 0xbd3af235 */ (T_MASK ^ 0x42c50dca)
#define T63    0x2ad7d2bb
#define T64 /* 0xeb86d391 */ (T_MASK ^ 0x14792c6e)

static void md5_process(md5_state_t *pms, const md5_byte_t *data /*[64]*/) {
  md5_word_t
      a = pms->abcd[0], b = pms->abcd[1],
      c = pms->abcd[2], d = pms->abcd[3];
  md5_word_t t;
#if BYTE_ORDER > 0
  /* Define storage only for big-endian CPUs. */
  md5_word_t X[16];
#else
  /* Define storage for little-endian or both types of CPUs. */
  md5_word_t xbuf[16];
  const md5_word_t *X;
#endif

  {                                     // NOLINT
#if BYTE_ORDER == 0
    /*
     * Determine dynamically whether this is a big-endian or
     * little-endian machine, since we can use a more efficient
     * algorithm on the latter.
     */
    static const int w = 1;

    if (*((const md5_byte_t *)&w)) /* dynamic little-endian */
#endif
#if BYTE_ORDER <= 0                     /* little-endian */
    {                                   // NOLINT
      // On little-endian machines, we can process properly aligned
      // data without copying it.
      if (!((data - (const md5_byte_t *)0) & 3)) {
        /* data are properly aligned */
        X = (const md5_word_t *)data;
      } else {
        /* not aligned */
        memcpy(xbuf, data, 64);
        X = xbuf;
      }
    }
#endif
#if BYTE_ORDER == 0
    else                                /* dynamic big-endian */
#endif
#if BYTE_ORDER >= 0                     /* big-endian */
    {                                   // NOLINT
      /*
       * On big-endian machines, we must arrange the bytes in the
       * right order.
       */
      const md5_byte_t *xp = data;
      int i;

#  if BYTE_ORDER == 0
      X = xbuf;                         /* (dynamic only) */
#  else
#    define xbuf X                      /* (static only) */
#  endif
      for (i = 0; i < 16; ++i, xp += 4)
        xbuf[i] = xp[0] + (xp[1] << 8) + (xp[2] << 16) + (xp[3] << 24);
    }
#endif
  }

#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

  /* Round 1. */
  /* Let [abcd k s i] denote the operation
     a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
#define F(x, y, z) (((x) & (y)) | (~(x) & (z)))
#define SET(a, b, c, d, k, s, Ti)               \
  t = a + F(b, c, d) + X[k] + Ti;                 \
  a = ROTATE_LEFT(t, s) + b
  /* Do the following 16 operations. */
  SET(a, b, c, d,  0,  7,  T1);
  SET(d, a, b, c,  1, 12,  T2);
  SET(c, d, a, b,  2, 17,  T3);
  SET(b, c, d, a,  3, 22,  T4);
  SET(a, b, c, d,  4,  7,  T5);
  SET(d, a, b, c,  5, 12,  T6);
  SET(c, d, a, b,  6, 17,  T7);
  SET(b, c, d, a,  7, 22,  T8);
  SET(a, b, c, d,  8,  7,  T9);
  SET(d, a, b, c,  9, 12, T10);
  SET(c, d, a, b, 10, 17, T11);
  SET(b, c, d, a, 11, 22, T12);
  SET(a, b, c, d, 12,  7, T13);
  SET(d, a, b, c, 13, 12, T14);
  SET(c, d, a, b, 14, 17, T15);
  SET(b, c, d, a, 15, 22, T16);
#undef SET

  /* Round 2. */
  /* Let [abcd k s i] denote the operation
     a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
#define G(x, y, z) (((x) & (z)) | ((y) & ~(z)))
#define SET(a, b, c, d, k, s, Ti)               \
  t = a + G(b, c, d) + X[k] + Ti;               \
  a = ROTATE_LEFT(t, s) + b
  /* Do the following 16 operations. */
  SET(a, b, c, d,  1,  5, T17);
  SET(d, a, b, c,  6,  9, T18);
  SET(c, d, a, b, 11, 14, T19);
  SET(b, c, d, a,  0, 20, T20);
  SET(a, b, c, d,  5,  5, T21);
  SET(d, a, b, c, 10,  9, T22);
  SET(c, d, a, b, 15, 14, T23);
  SET(b, c, d, a,  4, 20, T24);
  SET(a, b, c, d,  9,  5, T25);
  SET(d, a, b, c, 14,  9, T26);
  SET(c, d, a, b,  3, 14, T27);
  SET(b, c, d, a,  8, 20, T28);
  SET(a, b, c, d, 13,  5, T29);
  SET(d, a, b, c,  2,  9, T30);
  SET(c, d, a, b,  7, 14, T31);
  SET(b, c, d, a, 12, 20, T32);
#undef SET

  /* Round 3. */
  /* Let [abcd k s t] denote the operation
     a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define SET(a, b, c, d, k, s, Ti)               \
  t = a + H(b, c, d) + X[k] + Ti;               \
  a = ROTATE_LEFT(t, s) + b
  /* Do the following 16 operations. */
  SET(a, b, c, d,  5,  4, T33);
  SET(d, a, b, c,  8, 11, T34);
  SET(c, d, a, b, 11, 16, T35);
  SET(b, c, d, a, 14, 23, T36);
  SET(a, b, c, d,  1,  4, T37);
  SET(d, a, b, c,  4, 11, T38);
  SET(c, d, a, b,  7, 16, T39);
  SET(b, c, d, a, 10, 23, T40);
  SET(a, b, c, d, 13,  4, T41);
  SET(d, a, b, c,  0, 11, T42);
  SET(c, d, a, b,  3, 16, T43);
  SET(b, c, d, a,  6, 23, T44);
  SET(a, b, c, d,  9,  4, T45);
  SET(d, a, b, c, 12, 11, T46);
  SET(c, d, a, b, 15, 16, T47);
  SET(b, c, d, a,  2, 23, T48);
#undef SET

  /* Round 4. */
  /* Let [abcd k s t] denote the operation
     a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
#define SET(a, b, c, d, k, s, Ti)               \
  t = a + I(b, c, d) + X[k] + Ti;               \
  a = ROTATE_LEFT(t, s) + b
  /* Do the following 16 operations. */
  SET(a, b, c, d,  0,  6, T49);
  SET(d, a, b, c,  7, 10, T50);
  SET(c, d, a, b, 14, 15, T51);
  SET(b, c, d, a,  5, 21, T52);
  SET(a, b, c, d, 12,  6, T53);
  SET(d, a, b, c,  3, 10, T54);
  SET(c, d, a, b, 10, 15, T55);
  SET(b, c, d, a,  1, 21, T56);
  SET(a, b, c, d,  8,  6, T57);
  SET(d, a, b, c, 15, 10, T58);
  SET(c, d, a, b,  6, 15, T59);
  SET(b, c, d, a, 13, 21, T60);
  SET(a, b, c, d,  4,  6, T61);
  SET(d, a, b, c, 11, 10, T62);
  SET(c, d, a, b,  2, 15, T63);
  SET(b, c, d, a,  9, 21, T64);
#undef SET

  /* Then perform the following additions. (That is increment each
     of the four registers by the value it had before this block
     was started.) */
  pms->abcd[0] += a;
  pms->abcd[1] += b;
  pms->abcd[2] += c;
  pms->abcd[3] += d;
}

inline void md5_init(md5_state_t *pms) {
  pms->count[0] = pms->count[1] = 0;
  pms->abcd[0] = 0x67452301;
  pms->abcd[1] = /*0xefcdab89*/ T_MASK ^ 0x10325476;
  pms->abcd[2] = /*0x98badcfe*/ T_MASK ^ 0x67452301;
  pms->abcd[3] = 0x10325476;
}

void md5_append(md5_state_t *pms, const md5_byte_t *data, int nbytes) {
  const md5_byte_t *p = data;
  int left = nbytes;
  int offset = (pms->count[0] >> 3) & 63;
  md5_word_t nbits = (md5_word_t)(nbytes << 3);

  if (nbytes <= 0)
    return;

  /* Update the message length. */
  pms->count[1] += nbytes >> 29;
  pms->count[0] += nbits;
  if (pms->count[0] < nbits)
    pms->count[1]++;

  /* Process an initial partial block. */
  if (offset) {
    int copy = (offset + nbytes > 64 ? 64 - offset : nbytes);

    memcpy(pms->buf + offset, p, copy);
    if (offset + copy < 64)
      return;
    p += copy;
    left -= copy;
    md5_process(pms, pms->buf);
  }

  /* Process full blocks. */
  for (; left >= 64; p += 64, left -= 64)
    md5_process(pms, p);

  /* Process a final partial block. */
  if (left)
    memcpy(pms->buf, p, left);
}

void md5_finish(md5_state_t *pms, md5_byte_t digest[16]) {
  static const md5_byte_t pad[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
  md5_byte_t data[8];
  int i;

  /* Save the length before padding. */
  for (i = 0; i < 8; ++i)
    data[i] = (md5_byte_t)(pms->count[i >> 2] >> ((i & 3) << 3));
  /* Pad to 56 bytes mod 64. */
  md5_append(pms, pad, ((55 - (pms->count[0] >> 3)) & 63) + 1);
  /* Append the length. */
  md5_append(pms, data, 8);
  for (i = 0; i < 16; ++i)
    digest[i] = (md5_byte_t)(pms->abcd[i >> 2] >> ((i & 3) << 3));
}

uint64 MD5Hash(const unsigned char *s, const unsigned int len) {
  md5_state_t state;
  md5_byte_t digest[16];

  md5_init(&state);
  md5_append(&state, (const md5_byte_t *)s, len);
  md5_finish(&state, digest);

  uint64 *p = reinterpret_cast<uint64*>(digest);
  uint64 hash = *p;

  return hash;
}

uint64 MD5Hash(const std::string& s) {
  return MD5Hash((const unsigned char*)(s.c_str()), s.size());
}
